The present invention relates to the preparation of 2,4(1H,3H)-pyrimidinedione (uracil) from alkali formyl acetic acid alkyl esters by reaction with thiourea followed by reaction with hydrogen peroxide, without isolation of intermediates, in accordance with the equation: ##STR1##
Uracil is a product which has wide application as an industrial chemical, as an agrochemical or as a pharmaceutical starting product (Ind. Chem. Prod. Res. Dev. Vol. 17, No. 4 (1978) 278).
Uracil can be prepared by a number of methods, as described in part in the above-cited literature. The reaction of malic acid with urea in sulfuric acid containing sulfur trioxide has the disadvantage of the need for the disposal or processing or large amounts of dilute organically contaminated sulfuric acid. In the saponification of 2-thiouracil with chloroacetic acid and hydrochloric acid, the formation of mercaptoacetic acid produces an extremely unpleasant odor and the recovery of an odorless uracil is difficult and entails great losses.
The problem existed of preparing uracil in a high yield and purity while avoiding environment-polluting wastes by a method easy to perform on a technical scale, setting out from simple starting materials.